Thalweg

The word thalweg is of 19th-century German origin. The German word (modern spelling ) is a compound noun that is built from the German elements (since Duden's orthography reform of 1901 written ) meaning 'valley' (cognate with dale in English), and , meaning 'way'. It means 'valley way' and is used, with its modern spelling , in daily German to describe a path or road which follows the bottom of a valley, or in geography with the more technical meaning also adopted by English. ==Hydrology==

In hydrological and fluvial landforms, the thalweg is a line drawn to join the lowest points along the length of a stream bed or valley in its downward slope, defining its deepest channel. The thalweg thus marks the natural direction (the profile) of a watercourse. The term is sometimes used to refer to a subterranean stream that percolates under the surface and in the same general direction as the surface stream. ==Bouldering of thalweg of non-canalised rivers==

Slowing stream-bed erosion by bouldering a thalweg helps stabilize natural rivers' course and depth. Placing boulders along the thalweg helps to protect the channel's sedimentary erosion and deposit balance. In concurrence with this, doing so along an instream to form artificial sills helps to slow the sedimentary erosion and deposit of watercourses, while keeping the esteem (fishing, local wildlife, and recreation) and natural resources of the running water source intact. Placement of boulders along a thalweg and the creation of instream sills makes drying up rarer and less severe during late summer, and abates cases of severe sediment erosion and deposit in the spring and fall months when the flow rates are high, particularly if those rates have increased. Such partial infilling of a thalweg was prototyped in Meacham Creek in Umatilla, Oregon. ==Thalweg principle==

maritime borders in the Gulf of Oman and Persian Gulf are defined by the midpoint of the water The thalweg principle (also known as the thalweg doctrine or the rule of thalweg) is the legal principle that if the boundary between two political entities is stated to be a waterway without further description (e.g., a median line, right bank, eastern shore, low-tide line, etc.), the boundary follows the thalweg of that watercourse. A thalweg is the center of the principal navigable channel of the waterway (which is presumed to be the deepest part). The definition has been used in specific descriptions as well. The Treaty of Versailles, for example, specifies that "In the case of boundaries which are defined by a [navigable] waterway" the boundary is to follow "the median line of the principal channel of navigation." The precise drawing of river boundaries has been important on countless occasions. Notable examples include the Shatt al-Arab between Iraq and Iran, the Danube in central Europe (Croatia–Serbia border dispute), the Kasikili/Sedudu Island dispute between Namibia and Botswana (settled by the International Court of Justice in 1999), and the 2004 dispute settlement under the UN Law of the Sea concerning the offshore boundary between Guyana and Suriname, in which the thalweg of the Courantyne River played a role in the ruling. In the 20th century dispute between the USSR and China (PRC) over Zhenbao Island, China held that the Thalweg principle supported their position.{{cite book ==See also==